Java Development

[#1]

Summary This article applies to the BlackBerry® wireless devices based on Java™.

Description Some applications may not require a graphical user interface (GUI), but simply perform background processing for the user. The sample application below can initiate when a user selects it from the ribbon; however, no change appears on the screen and the user can select another icon from the ribbon and continue to use the BlackBerry device as they normally would. Selecting the same icon a second time cannot spawn a second instance of this sample, as the device is aware that the application has already been launched and will not create a second instance of it. The following sample will run indefinitely until the device is shut down: /** * GUILessApplication * * A sample application that appears on the ribbon * but does not have any user interface. */ package com.samples.guiLessApplication; import net.rim.device.api.ui.*; import net.rim.device.api.ui.component.*; import net.rim.device.api.ui.container.*; import net.rim.device.api.system.*; public final class GUILessApp extends Application { private BackGroundApp backGroundApp; public static void main(String[] args) { GUILessApp theApp = new GUILessApp(); theApp.enterEventDispatcher(); } public GUILessApp() { //Creates and starts a new BackGroundApp thread. backGroundApp = new BackGroundApp(); backGroundApp.start(); } //The thread that will run in the background. private class BackGroundApp extends Thread { boolean stopThread = false; public synchronized void stop() { stopThread = true; } public void run() { while (!stopThread) { //You would perform your processing here. //This sample just prints out a line //to the BlackBerry JDE Output Window System.out.println("Application is running"); //Sleep for 5 seconds to prevent the //application from running out of control try { sleep(5000); } catch (Exception e) { //Exception handling would go here. } } } } //Stop the thread on exit. protected void onExit() { backGroundApp.stop(); } }